Even though it was November (and thus spring in Argentina), conditions were already unusually dry—a portent of the worst drought that would hit Argentina in 70 years. Because of this, I found the occasional wet spot on the pavement as I walked the trails in La Reserva Ecológica Costanera Sur rather odd. At first I thought they were spit—the trails were popular on this day for runners and bike riders, but I quickly realized that those would have to be some truly ginormous spit wads based on the size of the splatter. It wasn’t long before I thought to look up, and this is what I saw on the branch directly above me:

Cephisus siccifolia spittle mass on unknown species of tree.

I knew right away this was the work of a froghopper, or “spittlebug,” a true bug (order Hemiptera) in the family Cercopidae. Spittlebugs are common in the eastern U.S. where I live and are famous for the spit-like wads of froth (“cuckoo spit” to some) within which the nymphs conceal themselves until they reach adulthood. Our eastern U.S. species, however, are most commonly seen on herbaceous plants rather than in trees, and the frothy masses they produce are fairly small—about the size of a real wad of spit (at least, according to my direct comparison when I was 12 years old). The spittle masses I was seeing today were enormous, frothy, liquid masses that literally dripped from the trees by their own weight—raining spit!

Nymphs produce bubbles by siphoning air into a channel under the abdomen.

I was about to move on when I noticed some movement in the spittle mass. A closer look through the macro lens revealed the tip of the abdomen of a nymph slowly circling around near the surface of the spittle and creating new bubbles as it did this. As one can imagine, living inside a mass of bubbly liquid presents a challenge to breathing, and the nymphs get around this problem by protruding the tip of the abdomen outside the spittle mass and taking in air through a tubelike canal below the abdomen (Hamilton & Morales 1992). Strong contractions of the abdomen inside the spittle mass eject air from the canal, resulting in bubble formation.

Nymphs partially exposed by removal of spittle mass.

I sent these photos to Andy Hamilton (Canadian National Collection of Insects, Arachnids and Nematodes), specialist in world Cercopidae, to see if there was any chance he might recognize the genus or species based on these photos. I noted that these were the biggest spittlebug nymphs I had ever seen (the individual in the first photo measuring ~10mm in length). Not only did he recognize them as belonging to the genus Cephisus, but he was actually in the process of finishing up a revision of the New World members of the tribe Ptyelini—Cephisus being the sole New World genus to represent the tribe. Based on its white coloration and occurrence as far south as Buenos Aires, Argentina, he suggested this must be C. siccifolia—a species that can sometimes achieve economic pest status (Ribeiro et al. 2005) but which still apparently needs to be properly recorded from Argentina (Hamilton 2012). Based on degree of wing pad development, Andy surmises the individual in Photo #1 represents a 3rd instar (if the 3rd instar measures 10 mm, can you imagine the size of the 5th instars?!). Andy asked me if I would grant him use of the photos in his soon-to-be-published revision (of course I agreed), and here is the plate with the photos (as well as an adult photographed by someone else) as it appears in his paper:

As Andy notes in his paper, it seems rather unusual that Cephisus is the only tribal representative in the New World despite having successfully colonized all of its tropical and subtropical mainland areas. There are several other genera in the tribe in Africa, which would suggest that the Ptyelini arose prior to the late Cretaceous rifting that separated South America and Africa into two continents. It is thus puzzling why the tribe went on to further diversify in Africa but not in the New World.

A tight crop of Photo #3 above was featured in Super Crop Challenge #15, for which Ben Coulter was the hands-down winner. Honestly I thought this might end up being a slam dunk challenge—people have gotten very good at designing Google search strings to come up with answers that in pre-internet days might have been impossible to find. Nobody stumbled upon the magic search string for this challenge—”MacRae Cercopidae” which pulls up the Hamilton paper and above plate as the very first result. Still, Ben used good old fashioned intuition based on the locality tag to correctly surmise the species and take the early lead in BitB Challenge Session #7. Congratulations, Ben!

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About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.

One Response to Raining spit

I suppose at any point over, say, the past 35 years I could have gone to the library or later the Internet and figured out what the deal was with the spittle masses I’ve happened upon innumerable times since I was a kid. But your explanation was more succinct (and the photos probably far better). Thanks for the information.

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